1. Field of the Invention
The present invention relates to the latching clutches for hydrokinetic coupling apparatus, especially for a motor vehicle. It also relates to the hydrokinetic coupling apparatus including such a clutch.
2. Description of Related Art
This clutch includes an input element intended to be linked in rotation to a driving shaft and an output element intended to be linked to a driven shaft, and is described in the document FR-A 2 749 634.
In the latter, the latching clutch includes at least one drive disc intended to be integrated, in such a way that it can be de-clutched, with the input element.
The disc is coupled to a first guide washer, linked elastically to a web integral with the output element. The first guide washer, in order to do this, has a toothing with axial spurs and the same goes for the drive disc intended to be clamped, such that it can be de-clutched, between a transverse wall, belonging to the input element, and a piston integral in rotation with the transverse wall, being mounted axially with respect to this wall. The toothing of the drive disc engages with the toothing of the first guide washer in such a way that the drive disc is linked in rotation to the guide washer while being able to be shifted axially with respect to it.
The spurs result from cutting-out and folding of the first metal guide washer. The first guide washer exhibits, at its outer periphery, an annular rim of axial orientation surrounding the web The object of the present invention is to pull part of this guide washer, and to do so simply and economically.
According to the invention, a latching clutch of the type indicated above is characterised in that the drive disc engages via its toothing with a toothing belonging to a crown ring and in that the crown ring is integral with the rim of the first guide washer. According to the invention, a hydrokinetic coupling apparatus is characterised in that it includes such a clutch.
By virtue of the invention, the first guide washer is made rigid since it is the crown ring which has the toothing engaging with that of the drive disc. The crown ring at least partly covers over the rim of this guide washer.
This guide washer is therefore devoid of drive spurs so that it is easier to manufacture.
The tooling for manufacturing the first guide washer is therefore simpler and less expensive. Moreover, this first guide washer can be thinner because of the presence of the crown ring.
The crown ring is a component which is simple to manufacture and stiffens the rim of the first guide washer, which is therefore less sensitive to centrifugal force phenomena. The crown ring, in one embodiment, has a thickness which is different from that of the first guide washer. This crown ring is advantageously thicker than the first guide washer, which makes it possible to reduce wear and to transmit more torque. In any event, the toothing may be of the desired amplitude, which makes it possible to dispense with heat treatments for hardening. For example, in the case of a toothing with alternating spurs and spaces, the spurs can be circumferentially wider and thicker than those of the prior art. By virtue of the crown ring, the toothing may be of any shape. It may be continuous without alternating spurs and spaces. The toothing, in one embodiment, is of axial orientation, and, in a variant, of radial orientation.
In one embodiment, the crown ring is applied and fixed, for example by welding, onto the rim of the first guide washer.
In a variant, the crown ring is of a single piece with the rim, being obtained by rolling from the rim. More precisely, the crown ring is rolled and folded in the reverse direction in order to double the thickness of the rim.
The crown ring is in intimate contact with the outer periphery of at least a part of the rim of the first guide washer. The crown ring may also, partly, closely follow the rounded part linking the rim to the inner periphery of the first guide washer.
When the toothing of the crown ring is of axial orientation, it can be installed on a circumference of greater diameter than that of the prior art.
The piston may thus extend radially beyond the average diameter of the springs acting between the first guide washer and the web which is integral with the output element.
It is thus possible to increase the outer diameter of the friction lining or linings associated with the drive disc. It is therefore possible to transmit more torque.
By virtue of the crown ring, it is possible to increase the axial size of the toothing in such a way that the crown ring can rotationally drive more than one drive disc. The crown ring makes it possible to have better control of the dimensions of the toothing.
The description which will follow illustrates the invention with regard to the attached drawings in which: